Vehicle steering system

Abstract

A motor vehicle steering system includes a transmission mechanism for transmitting a power of an electric motor to a steering mechanism. The transmission mechanism includes an intermediate gear meshed with a driving gear and a driven gear. The intermediate gear includes: an annular teeth forming portion rotatably supported by an outer periphery of a support shaft via a rolling bearing, the support shaft supported by a housing; and an annular elastic member interposed between an inner periphery of the teeth forming portion and an outer ring of the rolling bearing and interconnecting the teeth forming portion and the outer ring in a manner permitting torque transmission. An axis of the support shaft and an axis of the teeth forming portion are mutually offset, whereby an inner periphery of the elastic member is located eccentrically to an outer periphery thereof. A pre-load to press the teeth forming portion against the driving gear and the driven gear is provided by an elastic restorative force of the elastic member.

1 . A motor vehicle steering system comprising a transmission mechanism for transmitting a power of an electric motor to a steering mechanism,
 wherein the transmission mechanism includes a driving gear, a driven gear and an intermediate gear meshed with the driving gear and the driven gear,   wherein the intermediate gear includes: an annular teeth forming portion rotatably supported by an outer periphery of a support shaft via a rolling bearing, the support shaft supported by a housing; and an annular elastic member interposed between an inner periphery of the teeth forming portion and an outer ring of the rolling bearing and interconnecting the teeth forming portion and the outer ring so as to permit torque transmission therebetween,   wherein an axis of the support shaft and an axis of the teeth forming portion are mutually offset, whereby an inner periphery of the elastic member is located eccentrically to an outer periphery of the elastic member so as to allow elastic deformation of the elastic member, and   wherein a pre-load to press the teeth forming portion against the driving gear and the driven gear is provided by an elastic restorative force of the elastic member.   
   
   
       2 . A motor vehicle steering system according to  claim 1 , wherein the teeth forming portion is elastically supported in axial, radial and rotational directions via the elastic member. 
   
   
       3 . A motor vehicle steering system according to  claim 1 , wherein the intermediate gear includes a first metal sleeve and a second metal sleeve,
 wherein the first sleeve is rotatable together with the outer ring of the rolling bearing,   wherein the second sleeve is fitted in the inner periphery of the teeth forming portion so as to be rotatable together with the teeth forming portion, and   wherein the first sleeve and the second sleeve are interconnected via the elastic member so as to permit torque transmission therebetween.   
   
   
       4 . A motor vehicle steering system according to  claim 3 , wherein the elastic member includes a cylindrical portion interposed between an outer periphery of the first sleeve and an inner periphery of the second sleeve, and an end wall extended from one end of the cylindrical portion,
 wherein the second sleeve includes a cylindrical portion and an end wall extended from one end of the cylindrical portion, and   wherein the end wall of the elastic member is axially clamped between an end face of the first sleeve and the end wall of the second sleeve.   
   
   
       5 . A motor vehicle steering system according to  claim 3 , wherein the elastic member includes a protrusion or a recess elastically engaged with each of the first sleeve and the second sleeve so as to permit torque transmission.